


Mine

by how_about_no



Category: Mortal Instruments Series - Cassandra Clare, Shadowhunter Chronicles - Cassandra Clare, Shadowhunters (TV)
Genre: BAMF Alec Lightwood, Crack, Fluff, Fluff and Crack, Jealous Alec, Jealousy, M/M, literally he threatens someone
Language: English
Status: Completed
Published: 2016-06-01
Updated: 2016-06-01
Packaged: 2018-07-11 14:59:22
Rating: General Audiences
Warnings: No Archive Warnings Apply
Chapters: 1
Words: 2,513
Publisher: archiveofourown.org
Story URL: https://archiveofourown.org/works/7057195
Author URL: https://archiveofourown.org/users/how_about_no/pseuds/how_about_no
Summary: <blockquote class="userstuff">
              <p>What did Adam have that he didn’t? He always listened to Magnus’ stories and asked questions, interested to hear more. Both insecurity and anger crawled up Alec’s spine, a sensation he wasn’t unfamiliar with. The memory of Jace and Clary kissing in the middle of the institute came to mind and he shook it away.</p><p>This wasn’t the same. This was Magnus.</p><p>or</p><p>There's a visiting Shadowhunter from Idris that is a big fan of Magnus'.<br/>Alec is not a fan of him.</p>
            </blockquote>





	Mine

**Author's Note:**

  * Translation into Français available: [Mine](https://archiveofourown.org/works/9398654) by [sur1cat3](https://archiveofourown.org/users/sur1cat3/pseuds/sur1cat3)



> I really needed some jealous Alec in my life. This may become part of a series of jealousy fics but we shall see.

With a frown, Alec flicked aside a completed mission folder on the screen. They hadn’t been as productive this week. It could either be because of less demon activity, or because the shadowhunters of the New York institute just weren’t doing as good a job. Alec hoped it’s the former.

“Hey,” A voice came from behind him, and he turned around, his usual glare in place for anyone who interrupted him while he was working, “You’re Alec Lightwood, right?”

“Right,” Alec looked the man in front of him up and down. He was attractive, sure, but he wasn’t Magnus so Alec’s glare stayed strong, “And who are you?”

“Adam,” The man held out a hand, which Alec shook because it was curtesy, “I’m visiting from the LA institute.”

“Why?” Alec said, “Shouldn’t I have been informed about this?”

“I spoke with your parents.” Adam explained, which immediately put him in Alec’s bad books. He had the nerve to go _above_ Alec’s authority as acting head of the institute. He tried to express his distaste with a raised eyebrow.

“Okay,” He said slowly, “Then why are you talking to me?”

“Someone’s grumpy,” Adam pushed a hand through his sandy blond hair and Alec tried to stop himself from rolling his eyes. He couldn’t tell if he succeeded as rolling his eyes was such second nature that he didn’t notice himself doing it anymore, “I heard you’re close with Magnus Bane?”

“Close is one word for it.”

“Yeah,” Adam nodded, “I’m such a big fan of his. He’s done some great things. Like the time he fought Valentine in the uprising-”

“Yes, I know.” Alec snapped, already bored of this conversation. As much as he loved talking about Magnus, this guy was not someone he wanted to talk to, full stop.

Before Adam could say anything else, a portal opened up by the door of the institute. Alec knew who it was before they even stepped through. Magnus. His hair had no product in it, which Alec loved, but was tipped with blond like the night they had drinks. Well, it was also the night Luke nearly died but that was an unimportant detail.

His shirt was silk and flowing, with purple and blue patterns swirling into each other like marble. He was just as gorgeous as ever, and Alec could see the glitter around his eyes from here.

“Alexander.” Magnus walked over to him smoothly, as if he were floating, “Fancy seeing you here.”

“I work here.” Alec smiled for the first time that day when Magnus kissed him on the cheek.

“You do?” Magnus fake gasped, placing a delicate hand on his chest, “I would have appreciated that information earlier and I would’ve come over more often.”

“You come here every day, Magnus. If you came more often you’d be living here.”

“Hm,” Magnus hummed in thought, “Now there’s an idea.”

“Magnus Bane.” Adam spoke up and Alec frowned at him, having thought he would have walked away already, “I have been dying to meet you.”

“Adam Brown?” Magnus turned his attention away from Alec and smiled at the other man, “Are you the one who called me here?”

“Yes.” Adam smiled back, his eyes far too excited for Alec’s liking, “We have some questions about the Alpha of the New York werewolf pack. The council wants to know about your involvement.”

“Of course,” Magnus sobered, “Shall we go somewhere more private?”

“Perfect.”

Alec watched them walk away with his arms crossed. He had a bad feeling about this.

 

“He invited you over _again?_ ” Alec walked with Magnus as he headed for Adam’s room, “Hasn’t he got all the information he needs?”

“Yes,” Magnus nodded, waving a hand, “But he seems interested in my past, my adventures. He wanted to know about Peru as well. I don’t think it’s official council business anymore but I’m always grateful for willing ears for my stories.”

“I would listen to your stories.” Alec insisted, “You don’t need _him.”_

“Alec, dear, no offence, but you listen to my stories in a way where you want to know about _me,_ ” Magnus smiled, “And I love that, I do. But Adam listens to them as if I am the high warlock of Brooklyn, a figure in history.”

“Fine,” Alec clenched his jaw, “How about you get him to stroke your hair until you fall asleep too, because I wouldn’t mind getting that responsibility off my hands.”

“Alec-” Magnus started but Alec had already turned and started walking away.

What did Adam have that he didn’t? He always listened to Magnus’ stories and asked questions, interested to hear more. Both insecurity and anger crawled up Alec’s spine, a sensation he wasn’t unfamiliar with. The memory of Jace and Clary kissing in the middle of the institute came to mind and he shook it away.

This wasn’t the same. This was _Magnus._

He didn’t see Adam again until the next day, while he was hitting the punching bag with a venom that only came from imagining a certain someone’s face. Instead of Valentine, today it was the man himself.

“I feel sorry for whoever you want to punch like that.” Adam said, and Alec couldn’t help the smirk. If only he knew. The other man seemed to think it was because Alec thought his joke was funny, so he quickly schooled his expression into indifference.

“I can do worse.” Alec said, hoping it sounded like a threat, but Adam just huffed a laugh which wasn’t what he wanted at all.

“I’m sure you can,” He leant against the table at the back of the room, “Now I have a question.”

“If it’s council business, make an appointment.”

“Not council business,” Adam looked out into the institute instead of making eye contact, which made Alec’s suspicion grow, “How serious are you and Magnus?”

“What?” Alec couldn’t believe Adam would have the _nerve_ to ask that. He clenched his fists at his side to stop himself from punching anything that would get him into trouble. Be it the wall, or Adam’s smug face.

“I _said-”_

“I know what you _said,_ ” Alec took a step forward, thankful for his towering height, “The ‘what’ was more an implication of how ridiculous your question was, and how you have the nerve to ask it.”

“I was just asking, man, calm down.” Adam scoffed and Alec fumed.

“Leave.” Alec glared at him, “I need to finish my session and you’re in my way.”

“I’ll take that as a not-so-serious.” Adam moved to go past him, but was stopped by a hand on his shoulder.

“Stay out of my way, Adam.” Alec tightened his grip, “Don’t test me.”

He finally relented his hold, and Adam scurried away like a scared mouse. Alec smiled to himself, satisfied for now.

 

There hadn’t really been time for many dates in the last few weeks, so Alec was thankful when both he and Magnus had an evening free to spend some time together. They were sat on the couch in Magnus’ loft, chatting with their legs entwined when the buzzer went.

“Ah, that’ll be Adam.” Magnus jumped to his feet.

“Adam?” Alec gaped, “What’s he doing here?”

“I invited him,” Magnus said like it was obvious, making his way to the door, “He wanted to look at some of the antiques I have lying around and this was the only evening I had free.”

“But this is _our_ evening.” Alec complained, trying not to sound too petulant.

“It still is,” Magnus rolled his eyes, then buzzed Adam in like he wasn’t inviting Alec’s mortal enemy into his home, “He won’t be in the way, I’ve put it all in one room so he can look through it.”

“He doesn’t want the antiques.” Alec muttered to himself, and either Magnus didn’t hear him or chose to ignore the comment because he didn’t say anything.

“Magnus!” Adam’s annoyingly nice voice came from behind him, but he refused to turn around, “Great to see you, it’s been too long.”

“I can’t really chat, Alec’s here. The antiques are down the hall, first door on the left.” Magnus said shortly and Alec smiled, moving the golden liquid in his glass around.

“Oh,” Adam sounded disappointed, “Did I interrupt date night?”

“Oh no,” Magnus laughed, “Don’t worry about it.”

“ _Do_ worry about it,” Alec spoke up finally and pointed down the hall, “Antiques are that way. Go fetch.”

“Don’t be rude, Alec.” Magnus scolded him, “Would you like a drink?”

“He wouldn’t.” Alec stood up and faced the other too, “The antiques,” He enunciated each word so he couldn’t be dismissed, “Are through there.”

“All right,” Adam held his hands up, acting as if he was unaffected but Alec could see the fear in his eyes, “I’ll see you in a bit, Mags.”

“ _Mags_?” Alec mocked once the man had left the room, “Really?”

“I honestly don’t know what is going on with you, but it needs to stop.” Magnus crossed his arms.

“Sure,” Alec put his drink down on the table next to the sofa, “I’ll stop. Have fun with Adam.”

He shoved past the other man and ran down the stairs before Magnus could stop him. He didn’t storm out, and he wasn’t sulking. He was just done.

 

Later that evening, Alec was searching through his drawers for clean underwear when someone cleared their throat behind him.

“As much as I love this sight,” Magnus looked him up and down once he turned around, “Please get dressed so I’m not distracted from the matter at hand.”

“What do you want, Magnus?” Alec crossed his arms, feeling bare but stubborn.

“I’ve figured you out.” Magnus looked smug, as if he should win a prize for his discovery.

“Oh yeah?” Alec said, “You’ve figured out that I don’t like the fact that a guy is trying to get with you right under my nose? You figured that out? Well done.”

“As much as I appreciate your openness about your feelings lately,” Magnus held his hands out in front of him as if Alec was going to pounce, “This is a little far. Adam isn’t trying to get with me.”

“He asked me if you and me were serious.” Alec stepped toward his boyfriend, fully using his body to his advantage, “Why else would he ask that?”

“I don’t know,” Magnus shrugged, looking more and more flustered by the second, “Maybe he wants you.”

“He wants _you_ ,” Alec cupped Magnus’ neck with his right hand, “I’m not the one he is spending all his time with.”

“Well I want _you,_ isn’t that was matters?”

“No.” Alec stepped away, “I kind of want to punch him in the face.”

“Alexander-”

“Don’t _Alexander_ me,” Alec pointed at the very clearly sexually frustrated warlock, “If you don’t stop this- whatever _this_ is- with Adam, you’re getting none of this.” He gestured to his bare chest.

“Fine,” Magnus turned up his nose, “Until I get proof that Adam’s intent is what you say it is, I’m not stopping talking to him.”

“Have fun with that.” Alec raised an eyebrow and watched as Magnus muttered to himself while creating a portal to leave. He gave Alec another once over before he left with a huff.

 

Alec still seethed whenever he saw Adam and his smug smile. It’s like the man could tell Alec and Magnus had been fighting, and loved it. Only the fact that they were in the main room of the institute stopped him from roundhouse kicking the guy in the face.

At least right now, he wasn’t there. He didn’t know where he was but Alec just knew it was probably somewhere annoying. Or he was making wherever he was annoying. His phone buzzed in his pocket and he picked up without looking at the caller ID.

“Hello?”

“You were right,” Magnus hissed down the line, “You are always right, oh my goodness. He tried to kiss me, Alexander, get over here _right now._ ”

“What?” Alec was already on his way to the door, “Why are you whispering, is he still there?”

“I’m not good with confrontation.” Magnus mumbled.

“You’re the high warlock of Brooklyn, you’ve been in _wars,_ ” Alec laughed to try and keep the anger at bay until he got to the flat, “But you can’t tell a guy you don’t like him?”

“Well, Alec, I don’t like letting people down so if you could please get over here and stake your claim as quickly as possible that would be fantastic.”

“On my way.” Alec hung up and tried not the break the phone in his fist as he pulled his jacket on and ran out the door.

 

It was a while back that Magnus enchanted the door to let Alec in without a buzz. That meant it was a quick job storming into his apartment to find the two sat on the sofa, Magnus backed into a corner smiling uncomfortably, and Adam leaning in far too close.

“Sorry,” He said through gritted teeth, “Am I interrupting something?”

“Alec!” Magnus jumped up from the sofa, sagging with relief, but Alec barely glanced at him before setting his sights on Adam.

“Get up.” Alec said to him, face carefully blank, “Do you speak English? Get up!”

“Um-” Adam got to his feet and Alec stalked over to him, fully appreciative of his height advantage.

“Do you remember our conversation?” Alec started, feeling himself slip into his shadowhunter mask. He knew he could be scary and hoped that was in effect now, “About how you stay out of my way? I don’t know about you, but I thought that was a warning.”

“I thought you guys weren’t-”

“What?” Alec raised his eyebrows, “That we weren’t serious?” He laughed bitterly, “You don’t know the first thing about mine and Magnus’ relationship, and you don’t know the first thing about Magnus. He’s mine, not yours, not anyone’s but _mine._ Understood?”

“I- uh-”

“I _said,”_ Alec almost shouted, “Understood?”

“Yes.” Adam swallowed audibly.

“Yes, what?”

“Yes, sir?” Alec could see a bead of sweat crawling down the man’s forehead.

“Now get out,” He growled, “Before I punch you in your fucking face like I’ve been wanting to for a month.”

Adam ran. He moved with shadowhunter speed out of the door and down the stairs. Satisfaction curled in Alec’s stomach for the first time since the bastard arrived.

“Well,” Magnus clapped his hands together, “That was unbelievably hot.”

“You’re never leaving this apartment again,” Alec walked over to his boyfriend and pulled him in by the belt loops in his jeans, “And you better believe me next time I say someone wants you.”

“So,” Magnus tilted his head, a small, playful smile on his lips, “I’m _yours,_ huh?”

“All mine.” Alec smiled.

“I can deal with that.” Magnus said before pulling Alec in for a bruising kiss.

Though it was wonderful, Alec would have loved to have to opportunity to punch Adam just a little bit. When Magnus swiped his tongue over the seam in his lips though, he forgot all about him.

 

**Author's Note:**

> Thanks for reading!
> 
> visit me on tumblr- girlsf0rgirls


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